Early-est:     Tonga Islands    2026.03.28-10:17:10.72    q:C      mb:4.5*    Mwp:-    Mwpd:-    Td*T50Ex:-     fmamp_polarity:./hypo.1774693020267.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1774693020267.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1774693020267.mech.hash.thumb.jpg

Automatic solution - this event has not been reviewed by a seismologist
Automatically determined event information may be incorrect!

Earthquake Details:
Magnitude: mb: 4.5* [15]    Mwp: - [0]    Mwpd: - [0]
Region: Tonga Islands
Origin Time: 2026.03.28-10:17:10.72 UTC
Hypocenter: lat: -15.42°  lon: -173.23°  [+/-31km]    depth: 127km  [+/-22km]
Location Quality: qualityCode:  C     stdErr: 0.7s   assocPhases: 47   usedPhases: 19
minDist: 2.1°   maxDist: 147.3°   AzGap: 158°   2ndAzGap: 188°   atten: -1.41 [+/-0.24]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 17km   maxHorUnc: 31km   azMaxHorUnc: 145°
68%ConfEllipsoid:   semiMajorAxisLength: 38km   majorAxisAzimuth: 326°   majorAxisPlunge: 8°   semiIntermediateAxisLength: 24km   intermediateAxisAzimuth: 66°   intermediateAxisPlunge: 48°   semiMinorAxisLength: 17km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.3 [4]    Td: -s [0]    Td*T50Ex: - [0]    To: 1.1Xs [3]
Closest plate boundaries:
   Tonga / Pacific [subduction zone]: distance: ~60km
   Pacific - Tonga [oceanic transform fault]: distance: ~90km
   Tonga - Niuafo'ou [oceanic spreading ridge]: distance: ~110km
   Pacific - Niuafo'ou [oceanic transform fault]: distance: ~120km
Subduction geometry:    Zone: Kermadec-Tonga: DEBUG: error: [Errno 2] No such file or directory: 'gmt'    Slab depth at epicenter: error: evaluating slab depth: -999.9
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 YES (60km)
 no
 YES (90km)
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   -
   -
   -
Td*To:
     -
     -
     -
Mwp magnitude:
       -
       -
       -
Hypocenter depth:
       127km
       127km
       127km
Slab depth at epicenter:
       n/a
       -
       -
Tsunami and Rupture predictions (TEST!): No prediction: Event too small (Mwp<7.0) or too few Mwp readings (N<20)
./hypo.1774693020267.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1: strike: 37°   dip: 29°   rake: 179°
Nodal Plane 2: strike: 128°   dip: 90°   rake: 61°
Quality: azimuthalGap: -1°   stationPolarityCount: 16   misfitWeightCount: 3.3   misfit: 0.11   stationDistributionRatio: 0.75   meanDistP: 49.4   meanDistT: 48.2   qualityCode: D
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1774693020267.mech.fmamp_polarity.mechanism.jpg
First-motion Focal Mechanism (FMAMP_POLARITY_WAVEFORM):    (No solution available)
Nodal Plane 1: strike: 0°   dip: 0°   rake: 0°
Nodal Plane 2: strike: 270°   dip: 90°   rake: 90°
Quality: azimuthalGap: -1°   stationPolarityCount: 0   misfitWeightCount: -1.0   misfit: -1.00   stationDistributionRatio: -1.00   meanDistP: -1.0   meanDistT: -1.0   qualityCode: X
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity_waveform
./hypo.1774693020267.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (No solution available)
Nodal Plane 1: strike: 999°   dip: 99°   rake: 999°
Nodal Plane 2: strike: 324°   dip: 13°   rake: 135°
Quality: azimuthalGap: 158°   stationPolarityCount: 16   misfit: 0.99   stationDistributionRatio: 0.00   rmsAngDiffAccPref: 0.00   fracAcc30degPref: 0.00   qualityCode: E
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1774693020267.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1774693020267
Event info last updated: 2026.03.28-11:16:00 UTC
Event first association/location: 2026.03.28-10:27:03 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA